RMS-DC converters are used to convert the RMS (root-mean-square) value of an arbitrary signal into a quasi-DC signal that represents the power level of the signal being measured. Various techniques have been devised for performing RMS-to-DC conversions at frequencies ranging from DC to several GHz, some of which are disclosed in co-pending U.S. patent application Ser. No. 09/245,051 filed Feb. 4, 1999 and Ser. No. 09/256,640 filed Feb. 24, 1999 which are by the same inventor as the present application, and are incorporated herein by reference.
Performing accurate RMS-DC conversions over a wide dynamic range has proven difficult, especially at RF frequencies of several GHz. The need for wide dynamic range power measurement at very high frequencies has become more critical because the signals generated by modem communications systems such as those using CDMA (code division multiple access) have very wide instantaneous bandwidth (high crest factor), and because operating frequencies are continuously being pushed higher. One type of RMS-DC converter having an extended dynamic range is disclosed in co-pending U.S. patent application Ser. No. 09/473,309 filed Dec. 28, 1999, titled xe2x80x9cRMS-DC Converter Having Gain Stages With Variable Weighting Coefficientsxe2x80x9d which is by the same inventor as the present application, and is incorporated herein by reference.
An RMS-DC converter in accordance with the present invention includes a detector cell having a scaling factor which can be adjusted dynamically. The output from the detector cell is averaged to generate a final output signal.